Section 811 - Special provisions relating to agency project review jurisdiction and the shoreline restrictions1. Notwithstanding any other provision of this article, including the provisions of the land use and development plan and the shoreline restrictions, the following provisions shall apply in connection with the project review jurisdiction of the agency under section eight hundred nine and application of the shoreline restrictions either by the agency in the review of a project or by operation of section eight hundred six. a. Single family dwelling on existing vacant lot. One single family dwelling or mobile home shall be allowed to be built on any vacant lot which was on record on the date that this act shall become a law regardless of the overall intensity guidelines, or the minimum lot width provisions of the shoreline restrictions. For the purposes of this exemption, such a lot must not adjoin other lots in the same ownership, provided however, that all such lots in the same ownership may be treated together as one lot. In addition to the foregoing exemption, where the agency has jurisdiction, for a reason other than its location in a critical environmental area, of a single family dwelling or mobile home on a lot described in this paragraph which is owned by an individual who has continually owned such lot since May twenty-second, nineteen hundred seventy-three, it may not disapprove the project on any of the grounds specified in paragraph e of subdivision ten of section eight hundred nine, but may impose such reasonable conditions on the type and manner of placement of any individual on-site sewage disposal facilities as are in furtherance of the purposes of this article and in compliance with applicable standards of the department of health.b. Conversions of certain existing uses. Those structures in existence on the date that this act shall become a law that are associated with resort hotels, rental cottages and group camps shall be allowed to be converted from their previous use to individual single family residence use, notwithstanding the fact that such structures, as converted, do not conform to the overall intensity guidelines or the shoreline restrictions.c. Gifts, devises and inheritances. The mere division of land resulting from bona fide gift, devise or inheritance by and from natural persons shall not be subject to review by the agency. New land use or development on lots, parcels or sites conveyed by individuals, who on the date that this act shall become law own such land, to members of their immediate families by bona fide gift, devise or inheritance, shall be exempt from the overall intensity guidelines and the minimum lot size criteria specified in the class B regional project lists for the purpose of constructing one single family dwelling or mobile home on any such lot, parcel or site.2. Any pre-existing land use and development shall not be subject to review by the agency.3. Any (a) pre-existing subdivision of land, (b) any subdivision or portion of a subdivision that involves seventy-five or fewer lots, parcels or sites for the completion of which any or all permits and other approvals required by or pursuant to law were obtained after July first, nineteen hundred seventy-one and for which all such required permits were in full force and effect on July thirty-first, nineteen hundred seventy-three, or (c) individual single family dwelling or mobile home, erected or placed on any lot, parcel or site in any subdivision referred to in clauses (a) and (b) hereof which has been approved by the state department of health, shall not be subject to review by the agency, provided, however, that a subdivision or portion of a subdivision described in clause (b) hereof shall become subject to review by the agency on August first, nineteen hundred seventy-four if such subdivision or portion is not in existence on said date. Any individual single family dwelling or mobile home referred to in clause (c) of this subdivision hereof shall not be subject to the minimum lot width provisions of the shoreline restrictions.4. With respect to any land use or development or subdivision of land or portion thereof approved by the agency under its interim project review authority, in section eight hundred fifteen, such land use or development or subdivision or portion thereof may proceed in accordance with the terms of the approval and shall not be subject to further review by the agency so long as such land use or development or subdivision or portion thereof is substantially commenced and/or material expenditures and financial obligations have been incurred with regard to such land use or development or subdivision or portion thereof within two years of such approval.5. Any existing land use or development, including any structure being restored or rebuilt in whole or in part, being increased or expanded, whether in successive stages or at one time, to a total of less than twenty-five percent of its size or square footage at the date of enactment or when originally built or undertaken, whichever is later, shall not be subject to review by the agency. Any material increase or expansion thereafter shall constitute a reviewable land use or development if otherwise within the agency's review jurisdiction. In no case shall any increase or expansion violate, or increase non-compliance with, the minimum setback requirements of the shoreline restrictions. Notwithstanding the foregoing, a single family dwelling or mobile home may always be enlarged or rebuilt to any extent provided that it continues to be used as such, provided, however, that no such increase or expansion shall violate, or increase any non-compliance with, the minimum setback requirements of the shoreline restrictions.